Is there a set up where some remote service handles email exchange, and you just sync with it eg through POP style interfaces?
Yup, that’s signing up for a email provider. I wouldn’t call that self hosting since you’re just referring to email client software on your end to store the emails that are being synchronized at the email provider’s hosted server(s).
IMAP is sync so that might be what you meant. POP is even older but that’s for downloading only. And SMTP is for sending.
Those all still exist, most paid email providers still offer them just make sure to check before signing up. It’s harder to find that with free email providers, they usually disable IMAP/POP/SMTP on free accounts.
Looks interesting, always on the lookout for Android compatible Jellyfin music players with offline support. Maybe I’m mistaken but I think(?) last time I had looked at JellyBox it did not have offline support, nice to see it was added at some point.
Also, looks like there is already a Github issue about it but I was going to suggest having your app added to F-Droid if possible.
PS - Welcome to Lemmy!